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Old Jan 22, 2004, 1:45 PM   #1
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Default Inconsistent focusing on DRebel

I picked up a DRebel this past weekend with a Tamron 28-300 lens. I like the flexibility of the lens, bu I have found that the focusing is inconsistent in mostly indoor shooting thus far. Sometimes the focus is spot on, but often it is not. I have found that I can get better focus by using manual focus instead of AF. Is this a probelm with the lens or a weaknes in the DRebel AF? Thanks.

Willie
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Old Jan 22, 2004, 2:21 PM   #2
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Default Re: Inconsistent focusing on DRebel

Come to think of it, it is probably not the lense because I had the same inconsistency with my 50mm f1.8.

Bill
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Old Jan 22, 2004, 2:44 PM   #3
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Do you see the same problem if you use a single point focus?

I find that this usually resolves the issue for me.

Multi-point can get confused and the handbook does point out some situations where manual focus may be needed.

Brian
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Old Jan 22, 2004, 4:33 PM   #4
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Default Single Point Focus

I haven't tried single point focus. I'll give that a shot.

Willie
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Old Jan 24, 2004, 11:06 AM   #5
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Default Inconsistent focus

One thing to bear in mind is that the AF sensors are bigger than the markings shown in the viewfinder, take a look at http://www.knighttrain.freeserve.co.uk/ to see the areas covered by the sensors.

I also find that some lens are better than others, my 24-85mm appears to be worst at inconsistent focus.

In low light try increasing the ISO in case you have camera shake.
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Old Jan 24, 2004, 10:37 PM   #6
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Default I think I have a front focus problem

I took a bunch of photos today with my DRebel and 28-300 TamronXR. If I was close to the subject the focus was OK. If I was 15 feet across the room with the lens set to 28 mm, the focus was consistently several feet in front of the subjects. I could tell because there was a child closer than the others, but no where near the illuminated center AF point who was in perfect focus. Aperture was 4.0 and speed was 1/60 with flash. Is there any way to get this fixed, or should I take it back for a refund?

I am quite disappointed. When I focus manually I get some great shots. I don't want to pay for an autofocus DSLR and lens if I have to manually focus.

Willie
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Old Jan 25, 2004, 12:31 AM   #7
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Default Re: I think I have a front focus problem

Quote:
Originally Posted by unclewillie
If I was 15 feet across the room with the lens set to 28 mm, the focus was consistently several feet in front of the subjects. I could tell because there was a child closer than the others, but no where near the illuminated center AF point who was in perfect focus.
BreezeBrowser is a program that, among other things, shows the active focus points when the photograph was taken. You might want to download a copy and see exactly what is going on.

http://www.breezesys.com/index.htm

It's shareware, so you can use it for 30 days before registering it.

-jb
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Old Jan 25, 2004, 10:43 AM   #8
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jb, Thanks, but BreezeBrowser is unnecessary for the DRebel. If you use the Canon FileViewer utility that comes with the DRebel, It has an icon that enables the "Display AF points" option and it shows the active one in red. The active AF point is in the center in my front focus pics, right on my subjects.

Willie
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Old Jan 25, 2004, 12:29 PM   #9
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I haven't found inconsistencies in my DRebel. The autofocus is good, some lenses faster than others but that's a lens issue. Either you are not holding the shutter halfway and getting in focus prior to shooting the picture or you may have a bad camera. It is definately NOT a common issue across the board.
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Old Jan 25, 2004, 12:45 PM   #10
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Ohenry, I am glad your's works. I have owned an EOS 650 sincce 1985 so I know about pressing the shutter halfway down. I get the audio (beep) and visual (red dot) indication that the DRebel thinks it is in focus. There are enough posts here an on other boards about front and back focussing 300Ds and 10Ds that I don't think mine is an isolated case.

Willie
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